org.jruby.util.io.SelectorPool Maven / Gradle / Ivy
/*
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* Version: CPL 1.0/GPL 2.0/LGPL 2.1
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* License Version 1.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
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* Copyright (C) 2010 Charles O Nutter
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package org.jruby.util.io;
import java.io.IOException;
import java.nio.channels.Selector;
import java.util.ArrayList;
import java.util.List;
import java.nio.channels.spi.SelectorProvider;
/**
* This is a simple implementation of a hard-referenced java.nio.channels.Selector
* pool. It is intended to allow us to reuse a small pool of selectors rather
* than creating them new for each use (which causes problem for Windows and
* its socket-per-selector impl) or saving them per-thread (which causes
* problems when there are many not-quite-dead threads in flight.
*
* The selectors are kept open in the pool and you should call {@link #cleanup()}
* for releasing selectors.
*
* @author headius
*/
public class SelectorPool {
private final List pool = new ArrayList();
/**
* Get a selector from the pool (or create a new one). Selectors come from
* the default selector provider on the current JVM.
*
* @return a java.nio.channels.Selector
* @throws IOException if there's a problem opening a new selector
*/
public synchronized Selector get() throws IOException{
return retrieveFromPool();
}
/**
* Put a selector back into the pool.
*
* @param selector the selector to put back
*/
public synchronized void put(Selector selector) {
returnToPool(selector);
}
/**
* Clean up a pool.
*
* All selectors in a pool are closed and the pool gets empty.
*
*/
public synchronized void cleanup() {
while (!pool.isEmpty()) {
Selector selector = pool.remove(pool.size() - 1);
try {
selector.close();
} catch (IOException ioe) {
// ignore IOException at termination.
}
}
}
private Selector retrieveFromPool() throws IOException {
if (!pool.isEmpty()) {
return pool.remove(pool.size() - 1);
}
return SelectorFactory.openWithRetryFrom(null, SelectorProvider.provider());
}
private void returnToPool(Selector selector) {
pool.add(selector);
}
}